Many different types of concentrate bases and single strength juices are processed through a homogenizer to reduce pulpy fiber and make a uniform blend or puree. Pulpy juices are often homogenized to reduce particle size of the pulp and thus the apparent viscosity, such as “tight-end pulp” from a juice finisher.
Juice processing often requires both homogenization and high shear to create juice concentrates, concentrate bases, and slurries. Homogenization and high shear are required to reduce viscosity, eliminate undesirable insoluble particles (imperfections), and reduce the size of pulp and other fibers that are present in single strength or concentrate juices. Typically, juice concentrates are shear thinning thixotropic liquids. Reducing the viscosity reduces pressure drops in product pipelines and makes pumping easier. Reduced viscosity assists in the evaporation process and product dispensing, especially when high pectin is present.
Examples in juice and beverage processing include:
1. Reduction of viscosity of orange and grapefruit juices in a taste evaporator while minimizing insoluble imperfections. Current technology uses high-pressure piston style homogenizers placed within the evaporator between stages.
2. Reduction of particle size of pulp and/or fiber in orange and grapefruit juices, as well as a wide variety of concentrate bases and purees. The reduction is normally required for improved appearance and mouth feel. Current technology uses high-pressure piston style homogenizers placed after juice extraction and finishing.
3. Reduction of particle size of pulp in concentrate bases and single strength juices for permitting these products to be heated and/or cooled in a plate type heat exchanger. The plate type heat exchangers are restricted to products containing specifically sized particles.
4. Creation of stable oil/aqueous phase emulsion in blending citrus oils and other flavors as ingredients into a blended recipe. Flavor and minor component ingredient incorporation into blends are often problematic unless high-pressure homogenization is used. Many smaller companies accept a lesser quality product because of the high capital and maintenance costs of the equipment.
In many of the above processes, the current technology typically uses a high-pressure homogenizer. The high-pressure homogenizer uses a high-pressure piston pump to elevate the pressure of the liquid. A homogenizing valve discharges the liquid. The conventional homogenizer is expensive and consumes large amounts of horsepower because the required discharge may be in the approximately 2500 to 5000 psi range.
The use of batch type shear mixers is not practical in most cases because processes must be continuous flow. Replacing the homogenizer with an inline mechanical high shear pumping device is also not usually viable. Although mechanical shearing may be an alternative to the much higher shear homogenizing device, it requires much greater residence times. The inline mixer, even with multiple staging, cannot control the residence time.
While batch mechanical shear mixing and homogenization are easily scaled up from lab tests, it is difficult to predict the results achieved when the scale up involves inline mechanical shear mixing using a shear pumping device.
These same problems extend to the production of chemical solutions, micron-scale polymer beads, emulsions, suspensions, and other products that require blending, homogenizing, solubilizing, dispersion, or reduction of particle size.
Needs exist for improved and less expensive devices and methods to replace costly homogenizers.